GB2119714A

GB2119714A - Applying patterns to webs

Info

Publication number: GB2119714A
Application number: GB08312171A
Authority: GB
Inventors: Lars Karlsson; Erik Wallin
Original assignee: Diab Barracuda AB
Current assignee: Diab Barracuda AB
Priority date: 1982-05-06
Filing date: 1983-05-04
Publication date: 1983-11-23
Also published as: KR850001029A; DK202383D0; IT8320969A0; DE3315459A1; GB8312171D0; FR2526332A1

Abstract

The invention relates to a coating apparatus enabling coating a web (6) in patterns. The web is advanced closely outside a coating roll (2) which is coated with such as a pigmented plastisol and rotates in the opposite direction to the advancing web. Directly opposite the coating roll (2) there is a web depressor (9) divided into individually activatable portions along the length of the coating roll. When one of these portions is activated, the underlying portion of the web (6) is pressed towards the coating roll so that a strip-like portion of the web will be coated, the length of this strip being determined by how long the activation is, while non- activated portions are not coated. <IMAGE>

Description

SPECIFICATION Coating apparatus The invention relates to coating apparatus for plastisol compositions and silimar pigmented compositions in accordance with the preamble to Claim 1.

The principle for the application of such pigmented compositions is already known as reverse-roll-application and has been found very suitable for coating with plastisol compositions.

One object of the invention is to provide such coating apparatus, suitable for applying pigmented compositions in patterns, and especially patterns suitable for masking and camouflage sheets and the like. In such pattern application it has been usual up to now to use stencils, templates and the like, which only with difficulty can give long pattern repeats, however.

To increase the pattern repeat the stencil has been turned, e.g. according to US Patent 3 967 026.

The repeat length has then been increased considerably but is still limited. Furthermore one is still involved with stencils and templates, which reduce the possibility of variations. Each variant requires a new set of stencils.

It is a particular object of the invention to eliminate the need of special stencils, and to increase or even entirely eliminate the limited pattern repeat which has been previously unavoidable in practice. Another particular object is to achieve greater flexibility in the patterns, so that one is no longer tied to ready stencils.

This and other objects and advantages are achieved in accordance with the invention by the coating apparatus being given the distinguishing features disclosed in the characterizing portion of Claim 1.

By thus being individually enabled to guide web portions against the coating roll, each of a strip of web may be provided with pigmented composition or not, according as the setting, and thus within the framer of the strip width and the speed of resetting, arbitrary patterns can be obtained consisting of short or long strips of colour adjacent each other. Several coating apparatuses for different colours may be placed after each other for applying multicoloured patterns. The different web advancing means, which are arranged in a row, may consist of moving roll portions mounted at operating means.

Instead of roll portions there may also be used such as surfaces of plastics with a low coefficient of friction, e.g. polytetrafluor ethylene or the like.

The operating means can be of the compressed air of electromagnetic type.

It is suitable for the first of several such machines in a row to have a special device which provides the edge of the web with colour markings, serving as location marks for the continued process, whereby good register can be obtained between areas with different colours on the pattern picture, by having the markings at the edge optically sensed and used for controlling the activation of the depressing means for successive coating rolls, said means being arranged in a transverse row.

The invention' will now be described with the aid of the Figures depicting embodiments which are not to be considered as restricting.

Fig 1 illustrates a coating plant seen from one side.

Fig 2 schematically illustrates how a series of web advancing means in the plant according to Fig 1 can bring parts of the web against the coating roll associated with the plant. Fig 3 illustrates an embodiment of web advancing means in conjunction with another embodiment of a plant, seen from one side. Fig 4 illustrates a coating plant for applying three different colours.

Coating apparatus is schematically illustrated in Fig 1, where a web 6 is coated on being transferred from a supply roll 4 to a receiving roll 5, the web being trained along a path defined by guide rolls and past a coating roll 2 at a small distance therefrom, said roll being provided with a rather thick layer of coating composition and rotating in the opposite direction to the web travel.

A means 9 enables local urging of portions of the web 6 towards the coating roll 2, so that said portions come sufficiently near to the roll for the coating composition to be transferred, which otherwise does not occur.

The supply of coating composition to the coating roll 2 is arranged such that an auxiliary roll 3 is settable against the coating roll 2 to an adjustable nip. The nip is supplied with coating composition 7 and unillustrated means at the roll ends prevent the composition from oozing away.

The nip determines how much composition the coating roll 2 entrains. At a nip with the coating roll 2, a doctor roll 1 determines the final thickness, and the latter roll is scraped clean by a scraper 8. The function of this arrangement now described is already known in one connection where the web 6 is in contact with the coating roll 2 ali the time.

What is novel in the invention is a web advancing means 9 which can selectively urge portions of the web towards the coating roll 2. The principle of this will be seen schematically from Fig 2, where the means 9, which is mounted on an unillustrated boom, has individually maneuverable portions A-I. In Fig 2 the portion H is depressed, so that the web 6 is pressed down towards the coating roll 2 in this area. It is clear that a strip of web will be coated, corresponding to the width of H, while the rest of the web will be uncoated.

In Fig 1 it will be seen that after the coating roll 2 the web passes a drying means, e.g. a radiation heater, resulting in that the coating composition takes on a solid consistency. If the composition is a plastisol, gelation will take place.

Another embodiment is illustrated in Fig 3, where a coating roll 2 and a doctor roll 1 are partially submersed in a trough of pigmented composition. The thickness of the coating composition is determined by a scraper 12.

The means 9, of which a portion is illustrated in Fig 3, includes a boom 30 on which a series of compressed air-operated depressors 32 are mounted, each of which is operated by a compressed air-cylinder 31. The latter are controlled by solenoid valves which may be connected to a computer (not shown, which controls the supply of compressed air via hoses 34 and 33.

In Fig 4 there is illustrated an arrangement with three different sets of coating apparatus, each intended to apply a different colour. The colours are applied wet-in-wet and are afterwards heattreated in a radiation oven. It is also possible to locate a radiation oven after each apparatus, the problem of laying wet-in-wet being thus eliminated.

EXAMPLES In a plant according to the principle in Fig 4, the webs were arranged on steel reels with a length of 2500 mm and a diameter of 120 mm, for a maximum diameter of a full reel of 1 500 mm. The maximum width of the woven webs was 2000 mm, and the printing width was 1800 mm, divided into 9 zones with a width of 200 mm. The machine can print 4 colours, and for a relationship between the coating roll and web speed of 3 1 an amount of 50-150 g/m2 can be applied. The web and roll speeds are synchronized in a given relationship, and the maximum speed is 30 m/min.

After each of the three first coating rolls there is placed an infrared drier manufactured by IRT, Vänersborg, Sweden, which can dry, sufficiently for rolling up, 50 g/m2 plastisol at 30 m/min. An infrared drier of 50% greater capacity is placed after the last coating roll.

In the first of the coating apparatuses, a special depressor having a width of 10 mm is disposed at one edge, for providing edge markings. At the commencement of operation, markings with a length of 10 mm are laid, alternating with 10 mm spacings. This is done to a length corresponding to the pattern repeat which it is intended to use, and for the subsequent distances markings are made at every 30 mm. The markings are subsequently read by a photocell after each apparatus and serve to synchronize the control of the individually activatable compressed air devices of the web depressors.

With the aid of a programming means (suitably a computer) the different compressed air devices are activated, and coating takes place in the form of 20 cm wide strips with a length determined by a program. It is suitable to work with a pattern of the chess-board type, with modules of 20 x 20 cm, each square having a given colour applied, such squares being composed into larger areas, the program determining how the product will appear. For masking and camouflaging patterns there is the desire, for example, that said pattern will be determined by the type of nature where the camouflage is intended to be used.

In an advantageous utilization, the given colour pattern is applied on a specially prepared web, e.g.

a mat, so-called release weave, on top of the coating there being laid a further plastisol layer which can be of one colour. The layer thus combined can then be stripped from the release weave and constitute a masking film. It is also possible to apply a further multicoloured plastisol layer, thus obtaining masking patterns on both sides. The stripped-off film can be used as foliage camouflage, e.g. as described in US Patent 3 069 796.

Claims

1. Coating apparatus for plastisol compositions and the like, including a coating roll and means for applying thereto a layer of composition of a predetermined thickness, and means for advancing a web up to the coating roll for transferring composition from the coating roll to the web, the coating roll being adapted to rotate with a peripheral speed which is counter to the advancing direction of the web, characterized in that the web is arranged between the coating roll and a web depressor extending parallel to the coating roll and divided into a plurality of individually activatable portions disposed in a row, each of said portions being adapted for urging the underlying web portion, which otherwise is at a distance from the coating roll, into contact with the pigmented composition arranged on the coating roll, so that this web portion will be provided with a coating of said composition.

2. Coating apparatus as claimed in Claim 1, characterized in that the web depressor is arranged on a transverse boom and that for each activatable portion there is a compressed airoperated piston-cylinder means for operating said portion, and means for controlled supply of compressed air for operation.

3. Coating apparatus as claimed in Claim 1, characterized in that there are included therein a plurality of coating rolls mounted along the web and intended for coating said web with different colours.

4. Coating apparatus as claimed in Claim 3, characterized in that after each coating roll along the web there is a heating means for heat-treating the pigmented composition applied to the web.

5. Coating apparatus as claimed in Claim 3, characterized in that at the first coating roll there are means for providing the edge of the web with markings, there being optical detectors arranged at subsequent coating rolls for detecting said markings and sending electrical signals for synchronizing control of the depressors associated with said coating rolls.

6. Coating apparatus as claimed in Claim 1, characterized in that the activatable portions have surfaces of material with low friction facing towards the web.

7. Coating apparatus as claimed in Claim 1, characterized in that the activatable portions include rotatable and free-running rollers with rotation shafts which are parallel to the rotation shaft of the coating roll, said shafts being mounted in mounting forks attached to the piston-cylinder means.

8. Coating apparatus as claimed in Claim 1, characterized in that the means for applying pigmented composition to the coating roll include a first composition supply roll, parallel to the coating roll and with an adjustable nip in relation thereto, means for supplying composition to the nip, means for inhibiting composition from oozing sideways from the nipp, means for driving the first composition supply roll in the opposite direction to the coating roll, a second composition supply roll parallel to, and driven in the same direction as the coating roll, and having its distance to the coating roll settable, the second composition supply roll being arranged after the first composition supply roll, seen in the rotational direction of the coating roll, and a scraper blade for scraping the second composition supply roll.

9. Coating apparatus as claimed in Claim 1, characterized iri that the means for applying pigmented composition include a tank for the composition and in which the coating roll together with a doctor roll are partially immersed, the doctor roll being rotatably driven in the opposite direction to the coating roll and arranged axially parallel thereto, and a scraper adapted for limiting the thickness of the composition layer entrained by the coating roll at its rotating cylindrical surface from the composition containing in the tank.

1 0. Coating apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.